The study found that those with the gene variant were almost a quarter more likely to identify the correct emotion.

"In general, women do better on this test than men," said Sarina Rodrigues, an assistant professor of psychology at Oregon State University, who led the study.

"But we found a stark difference in both sexes based on the genetic variation."

The results of the study also suggest that the genes are linked to how carriers cope with stress.

Volunteers were subjected to a series of tests in which loud noises were played down headphones after a countdown on a screen.

The heart rates of all the students increased during the tests, but those of the carriers rose less than the others.

The researchers hope that the discovery of the genes could lead to a better understanding of conditions like autism, in which sufferers often struggle to understands how others are feeling.

A previous study has shown that a nasal oxytocin spray can increase the ability of autism sufferers to understand others emotions and feelings.

But the team, who published their findings in the journal Proceedings of the National Academy of Sciences (PNAS), caution against reading too much into their discovery.

Lots of people without the gene variation are able to understand and care about other people’s emotions, Rodrigues said.

"I tested myself and while I am not in the group, I'd like to think that I am a very caring person with empathy for others," she said.

"These findings can help us understand that some of us are born with a tendency to be more empathetic ... than others, and that we should reach out to those who may be naturally closed-off from people because social connectivity and belongingness benefits everyone."